AGB Quiz 33 Quiz InstructionsThis quiz consists of 20 multiple-choice questions.You will be awarded 5 marks for each correct answer. Question 1: Who first discovered the "X" chromosome as a determiner of sex during spermatogenesis in grasshoppers?McClungStevensWilsonBridges Question 2: In the marine worm Bonellia viridis, which environmental factor promotes the development of a free-swimming larva into a male?Settling in the deep ocean mudContact with the proboscis of a femaleExposure to high-temperature currentsHigh salinity in the surrounding water Question 3: What was the phenotypic basis of the mutation observed by Seth Wright in 1791, which led to the development of the Ancon breed of sheep?A dominant autosomal mutation for hornlessnessA mutation resulting in short-legged individualsA sex-linked lethal mutation causing sterilityA chromosomal inversion leading to dwarfism Question 4: In Bridges' genic balance theory of sex determination in Drosophila, what is the assigned female-determining strength of each X chromosome?0.51.01.52.0 Question 5: According to the genic balance theory, what is the sex index (X/A ratio) and the resulting phenotypic sex of a Drosophila individual with the chromosomal constitution 3A + XX?Ratio of 0.5, resulting in a normal maleRatio of 0.66, resulting in an intersexRatio of 1.5, resulting in a super femaleRatio of 1.0, resulting in a triploid female Question 6: Under the classification of intersexuality in farm animals, which of the following is true regarding true hermaphroditism in goats?It is determined by a dominant autosomal gene.It is 100% linked to the polledness trait.It can be eliminated by using polled breeding stock.The female type exhibits fully normal mammary glands. Question 7: Why is complete sex reversal considered incompatible with the development of mature mammals?Mammals do not possess any sex chromosomes in their somatic cells.Genital apparatuses differentiate early in embryonic life and lose plasticity.The default pathway of development in mammals is always male.Vertebrate sex hormones are local and do not circulate systemically. Question 8: Which bird demonstrated a documented case of complete sex reversal from a functional female to a functional male, as described by Crew in 1923?White Leghorn henBuff Orpington henRhode Island Red cockPlymouth Rock cock Question 9: During spermatogenesis in the haploid male honey bee (drone), how is the further reduction of the chromosome number prevented?The primary spermatocyte undergoes no chromosomal division, forming two diploid sperms.Chromatids do not separate during the second meiotic division.Only one division of chromatin takes place, with all 16 chromosomes passing into a single secondary spermatocyte.Chromosomes undergo endoreduplication prior to the first meiotic division. Question 10: Based on their biological effects, which class of mutations is the most common, constituting approximately 80% of all occurrences?LethalsVisiblesDetrimentalsStructural rearrangements Question 11: In the chemical structure of nucleic acids, what is the defined term for a unit comprising a pentose sugar bonded solely to a nitrogenous purine or pyrimidine base?NucleotideNucleosideCodonHistone Question 12: According to the genetic terminologies coined for the fine structure of a gene, what is a "cistron"?The smallest part of a gene that can undergo mutation.The unit of recombination, consisting of one or two nucleotide pairs.The unit of function, consisting of approximately 500 or more nucleotide pairs.The non-coding region of DNA involved in chromosome replication. Question 13: In the following question, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option.Assertion (A): Gynandromorphs cannot exist among vertebrate species.Reason (R): Vertebrates distribute sex hormones systemically throughout the entire body, which regulates sexual development uniformly.Both A and R are true, and R is the correct explanation of A.Both A and R are true, but R is not the correct explanation of A.A is true, but R is false.A is false, but R is true. Question 14: In the following question, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option.Assertion (A): In Drosophila, a 2A + X individual is phenotypically a sterile male.Reason (R): The presence of the Y chromosome in Drosophila is essential for male phenotype determination but is not required for male fertility.Both A and R are true, and R is the correct explanation of A.Both A and R are true, but R is not the correct explanation of A.A is true, but R is false.A is false, but R is true. Question 15: Evaluate the following statements regarding freemartinism in cattle and identify the correct combination:I. Most twins in cattle are binovular, arising from two corpora lutea and two separate ova.II. A freemartin female twin possesses a completely normal internal reproductive system but has male-like external genitalia.III. The chorionic membranes of opposite-sex fetuses fuse, allowing early-forming male sex hormones to direct the differentiation of the female co-twin.IV. Bovine freemartins do not experience heat and typically have underdeveloped mammary glands.Choose the correct combination:I, II, and III are correctI, III, and IV are correctII, III, and IV are correctI and IV only are correct Question 16: Consider the following statements regarding the characteristics of gene mutations:I. Muller estimated the mean life of a gene in Drosophila to be approximately 10,000 years.II. The rate of forward mutation is generally ten times lower than the rate of backward or reverse mutation.III. Chemical mutagens are capable of inducing both gene mutations and chromosomal mutations.IV. Two alleles of a gene within a diploid organism mutate independently of each other.Choose the correct combination:I, II, and III are correctII and IV are correctI, III, and IV are correctI and III only are correct Question 17: Identify which of the following statements are correct regarding the direct and indirect evidence supporting DNA as the genetic material:I. Somatic cells possess a constant amount of DNA, whereas gametes (sperm and egg) contain exactly half this amount.II. The absorption spectrum of nucleic acids matches the action spectrum of mutagenic ultraviolet radiation (around 2500–2600 Angstroms).III. Avery, MacLeod, and McCarty demonstrated that the transforming principle in Pneumococci was protein.IV. Transduction experiments in Salmonella show that bacteriophages transfer genetic material from one bacterium to another.Choose the correct combination:I, II, and III are correctI, II, and IV are correctII, III, and IV are correctI and IV only are correct Question 18: Match the mutation terms in Column I with their corresponding structural mechanisms in Column II:Column I:1. Transition2. Transversion3. Deletion4. InsertionColumn II:a. Loss of some portion of a geneb. Substitution of a purine for a pyrimidine or vice versac. Addition of one or more extra nucleotides to a gened. Substitution of one purine for another or one pyrimidine for anotherChoose the correct matching combination:1-d, 2-b, 3-a, 4-c1-b, 2-d, 3-a, 4-c1-d, 2-b, 3-c, 4-a1-a, 2-c, 3-b, 4-d Question 19: Match the sex types in Drosophila with their corresponding X chromosome and autosome sets (X:A ratio):Column I:1. Super female2. Intersex3. Normal male4. Super maleColumn II:a. 3X : 4A (Ratio 0.75)b. 3X : 2A (Ratio 1.5)c. 1X : 3A (Ratio 0.33)d. 1X : 2A (Ratio 0.5)Choose the correct matching combination:1-b, 2-a, 3-d, 4-c1-a, 2-b, 3-d, 4-c1-b, 2-a, 3-c, 4-d1-d, 2-c, 3-a, 4-b Question 20: Match the types of intersexuality in farm animals with their corresponding clinical characteristics:Column I:1. Freemartinism2. True hermaphroditism3. Male pseudohermaphroditism4. Behavioral intersexualityColumn II:a. Nymphomania and adrenal virilism in cattleb. Possession of both ovarian and testicular tissues (e.g., ovotestes)c. Co-twin to a normal male with fused chorionic blood vesselsd. Undescended testes with female-like external genitalia (resembling steers)Choose the correct matching combination:1-c, 2-b, 3-d, 4-a1-b, 2-c, 3-d, 4-a1-c, 2-d, 3-b, 4-a1-a, 2-b, 3-d, 4-c
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